The Captain's Duty
by Izzyaro
Summary: Five times Jim Kirk wasn't able to protect Bones, and one time he didn't have to.
1. Human Error

**So this little collection was started back in 2014, and was basically an excuse for me to write as much Bones whump as possible. Since it's been sitting in my files for nearly five years now, I thought it was about time it was posted. Most of it is finished and just needs tidying up, and so I will be updating every week. I hope you enjoy it.**

 **It's been a while, but many thanks to everyone at The Beta Branch for their support for this fic. It would still be a barely coherent one shot without you.**

 **Disclaimer: I own nothing.**

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"Hey, Bones, guess what?"

"You got another free drink."

Kirk pouted. "You're taking all the fun out of this, Bones."

He had to shout to be heard over the pounding music, but even with the flashing lights he could see McCoy roll his eyes.

"Well, one of us has to act our age."

Kirk pulled himself up onto the stool next to him and slung an arm around his best friend's shoulders. "Wow, you really need to relax."

"You're plenty relaxed for the both of us," McCoy growled. "How many of those things have you had?"

Kirk scratched his head. Things had started to get a bit fuzzy after the sixth. Or was it the eighth? "Who cares? We're on shore leave."

McCoy looked like he was resisting the urge to bang his head on the bar. Jim's grin widened and he tossed his latest drink back. There were definite perks to being the hero of Earth.

"Can you at least try to be careful?"

"Why?" Kirk slurred. "We deserve a break."

They had been running constant missions for nearly six weeks and the whole crew was on edge. Spock had actually begun to look irritated when his exacting standards weren't met, and the less said about Uhura and Scotty the better. The chance to take shore leave had been greeted with delighted approval from all quarters.

McCoy, however, still did not look happy. "I'm serious, Jim. Too many more and you're not going to be able to walk."

Kirk grinned at him. "That's the idea." A waiter appeared with yet another drink, but McCoy's snort dimmed his glee. "C'mon, lighten up. You were never this paranoid before."

McCoy glared at him. "You weren't the youngest Starfleet captain in history before."

"So?"

"Damn it, Jim-"

"Bones, just drop it," Kirk interrupted. "I can look after myself."

"Yeah, you're doing a brilliant job of that."

Kirk felt the first flickers of irritation. Honestly, the man seemed to think he was the same hothead he had been all those years ago, not a fully trained starship captain. "Just leave me alone, McCoy," he growled. "I swear you're acting more like my dad than my doctor."

McCoy twitched, and Kirk's anger disappeared at the hurt in his eyes. He opened his mouth, though whether to explain or apologise he didn't know, but his attention was rather abruptly derailed by a most curious scent. "What is that?"

McCoy frowned at him. "What the hell are you talking about?"

Kirk barely heard him. He could smell flowers, and perfume, and something that reminded him inexplicably of his favourite foods. But where was it coming from?

"Jim," McCoy hissed. "What is wrong with you?"

"That smell," Kirk managed.

McCoy's eyes narrowed. "Sweat and alcohol?"

"No, the other one. How can you not smell it?" It was like nothing he had ever experienced before.

McCoy's frown deepened. "Jim-"

"Excuse me," came a lilting voice, "but would you happen to be James Kirk?"

Kirk spun round and found himself staring into the deepest green eyes he had ever seen. Their owner was a tall woman, humanoid but for the brightly coloured plume of feathers she had in place of hair. And she was smiling at him.

Instinct immediately took over. "Jim Kirk," he said, rising to his feet. "Captain of the U.S.S. Enterprise."

The smile widened, showing a row of dazzling white teeth. "A pleasure to meet you, Captain. I am Ilmari."

Kirk took her hand and placed a kiss on the back of it. "I assure you, the pleasure is all mine. And it's Jim." He vaguely made out a snort from behind him but another blast of that scent diverted his attention. "You smell nice." He immediately felt his cheeks heat up in mortification, but Ilmari gave a melodious laugh.

"I created it myself. I am glad you like it."

"Very much."

Ilmari leaned over so that her mouth was right next to his ear. The proximity made his skin feel like it was on fire. "I can barely hear myself think in this place," she murmured. "How about we go somewhere more private?"

A year ago Kirk would have agreed without hesitation, if he hadn't already made the suggestion himself. A starship captain, however, had other priorities. "I don't know..."

"Please, Captain." Her fingers traced his jaw and he shivered under her touch. "It's not every day I get to meet someone like you."

Kirk knew he should be protesting. They were due back on the ship shortly and the captain had to set an example to the crew. As he stared into her eyes though, and breathed in her perfume, he found himself, perhaps for the first time in his life, at a loss for words. Ilmari's smile widened and he felt his resistance weakening.

Then a heavy hand came down on his shoulder. "Excuse me, ma'am," came McCoy's familiar drawl, "But I think the captain has had a little too much to drink and we really need to be beaming up soon."

Ilmari pursed her lips, but whatever she was about to say was interrupted by the outbreak of a fight between two Orions, an Andorian and a Tellarite. Ilmari rolled her eyes and leaned in towards him again. "Why don't we continue this discussion outside?" She didn't give Kirk a chance to protest, looping her arm through his and guiding him gently but firmly towards the door.

"Jim!"

"So, tell me about yourself, Jim," said Ilmari as they stepped out into the quiet of the night. What is it like to be a starship captain?"

Kirk smiled at her. "It's impossible to describe," he said. "Better than I ever imagined."

"Maybe you can try as you walk me home."

Kirk nodded. "All right." He had a vague feeing that there was something he was supposed to be doing, but whatever it was it couldn't be that important.

Kirk shook his head in an attempt to clear it as they made their way back to the main street. It was later than he had thought; no one was about but them and the silence was a little disconcerting after the noise of the bar. Absently he turned his eyes to the night sky, picking out the constellations with the ease of long practice. "Pretty stars."

He could hear the smile in Ilmari's voice as she replied. "So they are."

Kirk turned to smile back, only to lose his footing and stumble against her. "Sorry," he mumbled. "Must have had a few too many. Hear that, Bones? You were right." There was no reply. "Bones?" He tried to turn round to look for his friend, only for Ilmari to grip his arm.

"I think your friend's gone home."

Kirk frowned. "But he didn't say 'I told you so'. He always says it."

"Well, it looks like he decided to leave us in peace this time." Her fingers tightened round his bicep. "Wasn't that nice of him?"

"Very nice," Kirk agreed absently.

Except nice was not a word that Kirk would typically associate with McCoy. Brave, loyal, and compassionate to a fault, but nice? No. And he wouldn't let Kirk just go after the paranoia he had been displaying all evening.

Something was wrong here.

"Captain? Jim?"

Kirk closed his eyes, forcing away the fog that was threatening his senses. What was he doing? He knew better than to go off alone with a beautiful woman when he had responsibilities, even if she was the most beautiful, charming...

Kirk's hands clenched into fists. Ilmari was beautiful, yes, but no more so than any of the other women he had been attracted to. He shouldn't be reacting this strongly, even with all the alcohol he had drunk.

And where the hell was McCoy?

"Jim, what is it? Why don't you just come with me?"

Kirk felt a sudden irrational desire to do as she said, but this time he knew better than to listen. He untangled his arm from hers and stepped away. "I won't do that. Where is Dr. McCoy?"

Her eyes widened. "What are you saying, Jim? How should I know what happened to your friend?" There was nothing but hurt and confusion in her voice, but Kirk kept his eyes on Ilmari's.

So he saw the lie there.

"Jim, just tell me what's wrong?"

Kirk ignored her. His head still pounded violently and he was feeling increasingly queasy. The urge to listen, to obey, was still present too, ordering him to follow Ilmari's instructions with all his heart and soul.

Kirk had never been very good at following orders.

"Who are you?" he asked quietly. "What do you want with me?"

"Nothing! I just-"

"Answer the question!"

"I can't!"

"Why not?"

Ilmari didn't reply. Fear had replaced the affection in her face, and she was looking anywhere but at him. He opened his mouth to question her further, only to spin round again as footsteps sounded in the alley behind them. Approaching were the two Orions he had seen in the bar.

Orions.

Everything snapped into place. Why he had received so many free drinks. Why Ilmari had been so adamant she see him alone. What would have happened to him if she had. Bones had been right all alone.

Bones.

Horror was rapidly replaced by fury. He had been drugged and lied to, but that barely registered. McCoy had tried to warn him, and now something had happened to him. Kirk didn't know whether he was alive or dead, but he did know one thing. If Bones was injured in any way, Jim was going to make the people responsible burn.

"Please don't fight, Captain," said Ilmari quietly. "You can't stop this."

Kirk weighed his options. Two against one were usually perfectly acceptable odds, but his mind and vision were still fuzzy and he wasn't entirely confident in his ability to move without toppling over. The fact that both had phasers trained on him complicated matters somewhat too.

Kirk didn't care. These people had tried to capture him and done something to his best friend. His hands clenched into fists and he stepped forwards. They were going to pay.

Falling flat on his face was not supposed to be the next stage in the plan. There was a snort of laughter.

"Well, look at the great Captain Kirk now." The tone switched to a more businesslike one. "Stun him. Now."

Kirk struggled, but his limbs felt like duranium. Not even the knowledge of what awaited him could inspire any further movement, and it took all his strength to lift his head enough to meet Ilmari's gaze. If you're going to shoot me, shoot me," he rasped.

"Our pleasure," one of the Orions drawled.

Kirk slumped back to the ground. Spock would find him, he was certain of that, but being captured was so embarrassing. He heard the whine of phasers and braced himself for the rush of pain.

It never came.

"Captain, while convenient, the ground is not the most comfortable place of repose."

Kirk gave a huff of sheer relief. "Took your time, Spock," he slurred. He tried to raise himself up, only for a strong hand to push him back down.

"My apologies, Captain." There was a hiss of a hypo, and Kirk's nausea cleared enough for him to make out Spock and Security Chief Giotto bending over him.

"Thanks," he mumbled. He still felt awful, but at least he wouldn't fall over on the way to Sickbay. "How'd you even know I was in trouble?"

"You were out of our sight," said Giotto dryly.

"Hey!"

Spock's eyes glinted in a way Kirk had learned signalled amusement, even if his voice sounded nothing but professional. "Doctor McCoy informed us that you might require assistance before leaving the establishment – Captain!"

Kirk forced himself to a seated position, ignoring the way it made his head spin. "Need to find Bones."

Spock and Giotto exchanged a look. "We thought he was with you," said Giotto.

"He was," said Kirk quietly.

Giotto gripped his shoulder for a moment. "We'll find him." He stood up and began making his way back towards the bar, one hand on his phaser. Kirk staggered to his feet, suddenly very glad for Spock's hand at his elbow.

"He warned me," he mumbled. "He told me there might be trouble and I didn't listen."

Spock's grip tightened ever so slightly on his arm. "You are still under the influence of the drug, Captain. You were not to blame."

Kirk looked away, unable to meet his gaze. As he did so he caught sight of Ilmari lying on the floor near the Orions. Despite knowing everything she had done he couldn't help a twinge of remorse. Spock followed his gaze. "The planetary security forces are on their way."

"Good."

Spock glanced at him. "Captain-"

"Captain, over here!"

Kirk whirled round so fast he almost fell over. Giotto was waving at him from where he was crouched at the mouth of an alley. He felt a sudden rush of nausea, and was grateful when Spock steadied him again. "Come, Captain."

Kirk had expected something bad. Only that would have kept McCoy from coming after him. But the sight of Bones on the floor, his eyes closed and his face bone grey still left his head spinning until he was glad for Spock's reassuringly solid presence. McCoy wasn't supposed to be the one who got hurt. He was supposed to make snarky comments and stick Jim with hypos and tell him not to be an idiot. He wasn't supposed to get hurt because Jim was too arrogant to listen.

"Captain?"

Kirk pushed his guilt to one side, there would be time for that later. "How is he?"

Giotto looked up at him. "Blow to the back of his head, sir. Possible fractured skull, definite concussion." He traced the back of McCoy's head and bit his lip when his hand came away sticky with blood. "Sir, this really doesn't look good."

It took a moment for Kirk to get his vocal chords to work. "We'll transport back to the ship immediately. You stay here to coordinate with the security forces."

"Yes, sir."

Kirk knelt carefully next to McCoy to grip his friend's icy hand. "Spock, contact the Enterprise. Beam us back up." He was vaguely aware of Spock's hand coming to rest on his shoulder before the transporter beam took them away.

The next hour passed in a blur. Chapel and M'Benga were waiting with a pair of stretchers, which was fortunate as the stimulant Spock had given him wore off less than a minute after stepping off the transporter platform. Kirk wouldn't be at all surprised if his surprisingly devious First Officer had planned it that way. He was vaguely aware of being taken to Sickbay, and Spock standing watch by his bed while M'Benga flushed the remainder of the drug from his system. He might have thrown up a few times.

But when he did recover enough to think there was only one thing on his mind. "Bones?"

Spock said nothing, merely looked over to the next bed, and continued to say nothing while Kirk forced his way upright. His legs shook slightly, though from the after-effects of the drug or simple fear he couldn't tell, but he was able to lean on the bio-bed. He took a deep breath and looked down.

McCoy certainly looked better. He was still unconscious but he no longer looked like a living corpse and the bleeping of the monitor was reassuringly regular.

"Doctor M'Benga assures me that he will make a full recovery," said Spock quietly.

"Thank you, Spock," said Kirk. He took a deep breath. "How bad was it?"

"Captain-"

"I need to know."

Spock hesitated, but knew his commanding officer well enough not to try protesting further. "Severe concussion, sir. He was treated rapidly, and should regain consciousness within the next two hours."

Kirk could only nod. He gripped McCoy's hand and had to close his eyes at finding it no longer freezing. His mistake had not cost his best friend everything.

"Captain," said Spock. "I have analysed the traces of the drug found in your bloodstream."

Kirk reluctantly tore his gaze from McCoy's still face. "And?"

Spock clasped his hand behind back, switching unconsciously into report mode. "It acted on your judgement, reducing your inhibitions and making you more amenable to suggestion."

Kirk shivered. "You got that right." He shivered at the memory of how easy everything seemed before wrenching his mind away. "But how?"

"It seems to have been absorbed in aerosol form. Captain, do you recall any particularly strong odours? It is likely to have been pleasing to your senses."

Kirk closed his eyes for a moment. "Her perfume. She was standing right next to me." He frowned. "But why was I the only one affected?"

Spock seemed to shift slightly. "A drug in that form in such a crowded area would be inefficient. Too many people besides the intended target would be affected."

"So there must be an activating agent," Kirk finished. "Something only I came into contact with." The answer was obvious but he looked to Spock anyway. "My drinks?"

Spock nodded. "That is the most probable cause."

Kirk closed his eyes, white hot shame coursing through him. "He told me to be careful," he whispered.

"Captain?"

Kirk stared down at his friend's prone body. "Bones kept telling me to be more cautious, but I wouldn't listen. I thought no one could touch me." His grip on McCoy's hand tightened involuntarily. "I was an idiot."

"You were overconfident," Spock agreed.

Kirk shot him a sour look. "Thanks."

Spock's dark gaze softened almost imperceptibly. "You are human, Captain. To be human is to make mistakes."

"I am also a starship captain," Kirk shot back. "And starship captains can't afford to make mistakes."

Spock raised an eyebrow. "Now you are simply being illogical." He hesitated a moment then rested a hand on Kirk's shoulder. "I can assure you, Jim, that Dr. McCoy will not hold you responsible for this evening's events."

"Damn right I won't."

"Bones!"

McCoy flinched. "C'n we not shout around the concussed person, please?"

With an effort Kirk wrenched his jubilation under control. "Sorry." He glanced at Spock. "You said he wouldn't wake up for a while."

"Don' blame him," McCoy mumbled. "Sedatives can be tricky." His eyes narrowed as they scanned Kirk's face. "You all right?"

Kirk attempted a smile. "That was gonna be my question."

"I asked first."

"I'm fine," said Kirk. "They got all the drug out of me." He looked down at his hands. "You were right, Bones. I'm sorry."

"'m always right," McCoy muttered. "An' it wasn' your fault."

Kirk stared at him. "How can you say that? If I hadn't been so stupid-"

"They'd have waited 'til we left and stunned the both of us," McCoy interrupted. "I think I'm okay with this way."

"Well, I'm not," said Kirk flatly. "You could have been killed."

"Stop bein' so melodramatic, will ya? These things happen, and beatin' yourself up isn' doing anyone any good." He paused for an enormous yawn before blinking blearily at Spock. "Tell him, will ya?"

"Doctor McCoy is quite correct," said Spock. "The Orions would have resorted to more drastic measures, and those measures would have likely resulted in greater harm to both yourself and Doctor McCoy. Moreover, it is illogical to continue to blame yourself when the injured party does not."

Kirk didn't reply. It might be melodramatic and illogical but he couldn't help himself. He had been careless. He hadn't thought about his crew, and he hadn't even considered the thought that people might see him as a target. It had been reckless and irresponsible. He had been drugged, McCoy had been injured, and that was them being lucky. It could have been so much worse.

He hadn't been prepared for this and he should have been. He didn't deserve to be captain.

"He's beatin' himself up 'gain, Spock," McCoy mumbled.

"He does have a tendency to do so, Doctor," Spock agreed. "No matter how misplaced such emotions might be."

Kirk glared at them. "I'm right here, you know."

McCoy raised an eyebrow. "So? You're clearly not listenin' to either of us."

"You're the ones who aren't listening," Kirk protested. "Don't you care that I almost got you killed?"

"Will ya stop sayin' that? Jim, it wasn't your fault." He pushed himself to one elbow, waving away Kirk's offer of help. "Don't fuss either." He fixed Kirk with a sharp look. "Now you listen to me, and don't give me all that bull about captains not making mistakes. You only human Jim, more than that, you're a young one. Of course you're gonna make mistakes; how else are you going to learn?"

"Mistakes aren't supposed to endanger my crew," Kirk muttered.

"Or maybe they're just the ones that'll stick the best," said McCoy gently. "Jim, this wasn't your fault. And if you keep sayin' otherwise I'll stick you with a hypo."

"You're in bed with a healing concussion."

"Then I'll get my Vulcan nurse to do it for me." He grinned up at Spock, who looked like he was resisting the urge to roll his eyes.

"I have never entered the medical profession, nor do I have any intention of doing so, Doctor."

"Thank goodness for that," McCoy remarked. "I pity the patients who'd have to suffer what passes for your bedside manner."

"You do have plenty of experience with that situation, Doctor."

"Don't insult me until you've tried it, you pointy-eared hobgoblin."

"That's enough," said Kirk firmly, but he couldn't keep the smile from spreading across his face. Seeing McCoy sitting up and engrossed in the familiar banter had done much to settle his nerves. He caught the look that passed between the two of them, and guessed that the display had been for his benefit, but he couldn't bring himself to care. McCoy's hazel eyes twinkled as he looked up at Kirk.

"Feeling better then?"

Kirk looked sheepishly down at his hands. "Yeah." He took a deep breath and looked up. "I am sorry, Bones."

McCoy patted him on the knee. "I know. Just don't do it again."

"I won't," said Kirk quietly. This would not happen again.

McCoy gave a small smile. "Then for pity's sake stop worryin' about it."

Kirk opened his mouth to protest, but the gleam in the doctor's eyes warned against it. "I'll do my best."

"Good," McCoy grumbled. "Why do you always complicate things?"

Kirk gave a sheepish shrug but Spock's eyes narrowed. "Doctor, might I suggest you lie down? Grey is not a healthy colour for your countenance."

McCoy grimaced. "For once I agree with you." He lay back down, unable to suppress the wince that crossed his face as his head touched the pillow. Kirk hovered over him anxiously.

"You sure you're all right?"

"I'll be fine," McCoy mumbled. Sleep was evidently catching up on him, but he managed to focus one eye on Kirk. "Remember what I said. Don't beat yourself up."

"I know," said Kirk quietly. "I'm only human."

"'xactly." A ghost of a smile touched his lips. "See Spock doesn't have that excuse."

Spock raised an eyebrow. "I would not need it."

"Yeah, yeah, Vulcans don't make mistakes."

"Precisely, Doctor."

"Oh shut up."

Kirk leaned back against the wall and closed his eyes. It would take some time for him to stop blaming himself for what had happened. He couldn't help that. But knowing that neither of his best friends blamed him helped more than he had thought possible.

He would remember the experience. He would learn from it. And he would make sure that it never happened again.

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 **Any feedback would be appreciated.**


	2. Command Decisions

**This actually the first piece I wrote for this series, but it fitted better slightly later in the timeline. I hope you enjoy it.**

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From the first day he stepped onto the Enterprise, Jim has known that commanding a starship was going to be difficult. The months that have passed since the start of his five year mission have done nothing to assuage those fears. Jim likes adventure as much as the next person, more so in fact, but would a mission where everything went according to plan be too much to ask?

Take today. All they were supposed to be doing was transferring supplies to a vessel in distress. Easy, uncomplicated, a chance to take a break from the monotony of star charting.

He'd really like a mission to actually go according to plan. Preferably one that didn't end with a psycho chaining him up.

"You could make this so much easier on yourself, Captain."

Kirk glares at their captor. He'd identified himself as Jackson Kelvin, but if that was his real name Jim will eat his shirt. "I don't care," he growls. "It's not happening."

"What exactly do you think you're going to gain from this?" McCoy demands from the opposite wall. He's bound the same way Kirk is, his wrists shackles either side of his head, and captivity has done nothing for his temper.

"I told you, Doctor," Kelvin drawls. "I want the command codes for your ship."

"And I've told you you're not getting them." The thought of what Kelvin could do with those codes is not a pleasant one. No doubt Spock would be able to counteract him given time and opportunity, but if there's one thing Kirk refuses to put at risk it's his ship.

Kelvin sighs. "You say that now. I'm sure I can convince you otherwise."

McCoy snorts. "Good luck with that."

Kelvin's glare switches to McCoy, and Kirk takes the opportunity to test the restraints. It's about as effective as the last dozen times he's tried. "What do you mean by that?" Kelvin demands.

McCoy raises an eyebrow. "I've been trying to change his mind for years and never had any luck."

"Bones!"

"Well it's true. You're as pig-headed as a Tellarite. Or a Vulcan." He tilts his head to one side. "Don't tell Spock I said that."

Jim has to grin at his friend's incorrigibility, but all amusement is erased when Kelvin sighs and draws an old-style gun from behind him. "Yes, but as you see, I have alternatives." His eyes gleam with a light that doesn't look entirely sane. "I'd really be careful, Doctor."

Jim knows the look that enters his friend's eyes and shoots him a warning glare. The last thing they want is to antagonise the madman.

He isn't surprised when it has no effect.

"Maybe it's you who should be careful," Bones snaps. "Is that thing even legal?"

Jim's eyes narrow. "As a matter of fact, no. Projectile based weapons were outlawed decades ago."

Kelvin laughs. "I know, but I couldn't resist." He strokes the gleaming barrel. "This, gentlemen, is a Nagant M1895. One of the most famous guns of old Russia. Cost me a small fortune, but it was worth every penny."

Sulu would be in heaven now, let alone Chekov, but all Jim can think about is just how much damage that sort of weapon can do. "I don't care about the history," he snarls. "What do you want?"

Kelvin weighs the revolver in his hand easily, and Jim has a sudden rush of foreboding at the anticipation in his eyes. "Tell me, Captain; have you ever heard of the old Earth game Russian Roulette?"

Kirk's breath hitches. He can't be thinking what Jim thinks he is. No one is that insane. Then he remembers some of the things he's seen and looks at the expression on Kelvin's face and knows he's mistaken. Opposite him McCoy's face flushes with rage-filled understanding.

"You sick bastard-"

"Enough, Bones," Jim snaps. He let his lip curl, refusing to let Kelvin have the satisfaction of seeing just how rattled he is. "I've heard of it, but it won't do you any good. You're not getting any of those codes."

Kelvin sighs and twirls the gun round his finger and Jim's heart sinks. "I thought as much. Starship captains are known for being free with their own lives."

"Then why..." His voice trails off abruptly as fear even more potent than a moment ago rushes through him. "Don't you dare!" Not this, anything but this...

Kelvin laughs, a manic sound that sets Kirk's teeth on edge. "I see you've figured it out, Captain. Not bad." His smirk widens as he raises the weapon and points it straight at McCoy. "Let's see if you consider your friend's life of more value."

McCoy glares at him. "If you think for one second that this is going to work-"

"Bones, shut up," Jim rasps.

"Jim-"

"I said that's enough."

Kelvin glanced between the pair of them, his blue eyes dancing with glee. "Well, well, well. Looks like I was right."

"Except you're not," McCoy snarls. "He's not giving you anything."

Kelvin folds his arms, his grin widening. "Then why doesn't he tell me that himself?"

For the first time in a long time Kirk finds himself at a loss for words. This isn't supposed to happen. It's supposed to be him who gets threatened and injured, not McCoy. McCoy, who would treat his worst enemy without a second thought, and who has never let Jim down. Kirk refuses to lose him to an over-ambitious pirate.

And yet Kelvin won't just have command of the Enterprise with those codes. He'd be able to access every Starfleet database; mission reports, orders, personnel files, technological information... The consequences don't bear thinking about.

"Jim?"

Kirk wrenches his mind back to the present to find McCoy staring at him. The doctor's eyes are wide with rising concern, and it's almost enough to break Jim's resolve.

But McCoy would never forgive him if he did that. And he would be right not to. Jim straightens as best he can and looks Kelvin straight in the eye.

"Doctor McCoy is correct," he says as calmly as he can manage. "Starfleet officers do not submit to intimidation and interrogation."

For a moment doubt shows in Kelvin's eyes, and Kirk mentally thanks Spock for helping him perfect his poker face. If Kelvin can just realise how foolish this course of action is...

But then the doubt is gone, and the last of Kirk's hope dies as Kelvin reaches into a pocket and withdraws a single bronze bullet. "We shall see."

Kirk's hands clench into fists as Kelvin loads the revolver. The movements are quick and practised, and Jim wonders how many other people have had to experience this before forcing the thought aside. He can't afford another distraction. He knows Spock will be working on finding them, but whether he will arrive in time or not is another matter. If they're to get out of this undamaged, they can't afford to rely on anyone but themselves.

"There's no need to do this," he says. He forces himself to keep the scowl from his face, instead putting all the charm he's famous for into his voice and body language. "Why don't you tell me why you're doing all this? Maybe I can help?"

He ignores the incredulous look McCoy shoots him in favour of watching Kelvin, but isn't surprised when the man just snorts. "You can't help me, Captain. Besides," he spins the cylinder, "this way is much more fun."

Kirk swallows, desperately searching for an alternative, but the gleam of the spinning cylinder is almost hypnotic and he finds his usual eloquence has fled.

"So glad you're not bored," McCoy mutters.

Kirk's throat tightens. "Bones..."

"I know, Jim," says McCoy quietly. "I know."

What has he ever done to deserve the friendship of a man like this? McCoy continues to glare at Kelvin, and the familiar glare is surprisingly heartening. Only someone who has known him as long as Kirk has could see the slight tremor of his hands and the flicker of fear in his hazel eyes.

"Well isn't that sweet?" Kelvin mutters. "Wonder if you'll feel the same way in a minute."

"You bet your ass we will," McCoy snarls, and Kirk once again wonders if it's really possible to burst with pride. Then Kelvin points the gun at McCoy's head and it's all he can do to keep his knees from buckling.

Kelvin raises an eyebrow at him. "Last chance, Captain."

Kirk looks him straight in the eye. "Go to hell."

"Maybe," Kelvin agrees. "But I won't be the first there." He points the gun straight at McCoy's head and pulls the trigger.

 _Click._

Kirk feels like throwing up. The gun might not have been aimed at him but the adrenaline rush is still enough to make him dizzy. Then he sees the way McCoy's face has turned chalk white and is furious with himself. "Bones?"

McCoy is shaking visibly, but he nods. "I'm fine, Jim."

"This time," Kelvin agrees. "Have you reconsidered, Captain?"

Kirk hesitates, but the glare McCoy shoots him warns him not to even consider it. "No."

Kelvin sighs and raises the gun, and McCoy isn't the only one who flinches. "Very well."

 _Click._

Blood pounds in Kirk's ears, and his knees are once again weak. McCoy has also slumped in his restraints, his breathing harsh and ragged. Kelvin looks at Kirk and raises an eyebrow, and it takes all Kirk's willpower to meet his gaze.

"No."

The gun comes up again, and Kirk has to close his eyes. He hates himself for it.

 _Click._

There's a low hiss, and Kirk's eyes fly open. McCoy's hands are clenched and blood is trickling down his wrists from where his nail have bitten into his palms, but it's the barely concealed terror on his face that causes Kirk to snap. "Stop this! It's me you're angry with; threaten me!"

"Jim," McCoy hisses, but Kelvin's laugh drowns him out.

"That's not the way this works, Captain."

"Yes," Kirk grinds out. "Because you're a coward who can only attack a doctor."

"What d'ya mean by that?" McCoy mumbles, but Kelvin's eyes have narrowed.

"What did you just call me?"

Kirk ignores the widening of McCoy's eyes in favour of sneering at their tormentor. "You heard me. You're nothing but a cowardly, pathetic son of a-"

Kelvin moves faster than Kirk thought possible. The revolver comes up and Kirk's world explodes into pain.

"Jim!"

Spots spin in front of Kirk's eyes, and he finds his knees buckling. He vaguely hears McCoy swearing, and spares a moment to admire the sheer creativity his friend possesses before the pain once again blocks out all thought.

"Damn it, Jim!"

"'m all right," he slurs.

"Like hell you are. You leave him alone you pig-headed Neander-oof!"

The pained grunt does what the swearing couldn't. "Bones!" There's a sudden storm of coughing, and Kirk's concern deepens to outright terror. "Bones!" He forces his eyes open, only to clamp them shut again when the light threatens to make him throw up.

"I'm fine, Jim," comes McCoy's voice. It's no reassurance; McCoy is usually good at hiding pain, too good in fact, but he's doing a terrible job now, and that's more than enough to override Kirk's own discomfort. He opens his eyes again, more carefully this time, and squints towards the doctor.

McCoy is nearly bent double, but already he's regaining his footing. He meets Kirk's eyes and his lips twist into a hideous facsimile of a smile. "Look at us," he wheezes. "Spock's never gonna let us go out without a security detail again."

Kirk manages a grin, ignoring the way it strains his battered features. "You maybe," he manages. "I can override him."

"Not on my watch you won't."

"Enough!"

Kirk is all too happy to return his glare to Kelvin. The man's face is flushed with rage and his knuckles are white on the gun. Kirk manages a savage grin. "What's the matter? Feeling a little out of control?"

Kelvin just gives a thin smile. "Do I need to remind you which of us is holding the gun?" He raises the weapon in question, and any sense of triumph is immediately erased by the tension that appears in McCoy's body. Kelvin's grin widened and he turns to Kirk. "Well, Captain?"

Kirk stares back. His cheek throbs, and part of him acknowledges that the bone is cracked, if not broken, but the pain is manageable and he disregards it. "Don't do this."

"We've been over this, Captain," says Kelvin with a sigh. He spins the gun thoughtfully in his hand. "The M1895 carries seven rounds. We've had three. That means there's a 25% chance that the next one will have the bullet. How do you like those odds, Captain?"

Kirk's hands clench. "Kelvin, please..."

Kelvin raises an eyebrow. "Are you actually begging?"

"Jim-"

"Yes," Kirk snaps, because there's a time for pride and this sure as hell isn't it. "I'm begging you not to do this."

Kelvin studies him with something remarkably like curiosity. "Intriguing. But will you give me the codes?"

Kirk looks at McCoy. It's impossible not to see the pain and stress in the doctor's face, but it's the complete lack of hope that makes his blood burn. McCoy doesn't give up hope, it's just not in his nature. But this time, when this is at risk...

"No," he says quietly.

Kelvin gives an exaggerated sigh and pulls the trigger again.

 _Click._

"Damn it," McCoy chokes.

Kirk straightens up. "Bones? Bones, look at me!"

It takes McCoy far too long to raise his head. "I'm okay," he mumbles. "Sorry."

Any other situation and Kirk would laugh. Only McCoy would think of apologising for something like this. As it is, all he can do is shake his head. "Me too."

Kelvin rolls his eyes. "Touching. Truly touching. Captain, there are three rounds left. Are you really going to let this go on any further?"

Kirk doesn't, can't, take his eyes from McCoy's trembling body. "I have no choice," he whispers.

A one in three chance. If there are gods out there, let them be on his side now.

 _Click._

Kirk has to force himself to start breathing as McCoy's knees buckle and he slumps forward in his restraints. "Talk to me, Bones."

A low whimper is his only response, and Kirk thinks his heart is going to break. "I'm sorry. I'm so sorry."

McCoy still doesn't reply. Kirk looks at Kelvin. He never thought he'd ever hate anyone as much as he did Nero. He was wrong. "I'm going to kill you."

Kelvin laughs. "You can try." He leans against the wall, once again playing with that infernal gun. "Two more chances. A fifty-fifty chance." Blue eyes gleam and Kirk has to fight back a shudder. "What are you going to do if he survives this time?"

Kirk can't think. He can't breathe. He would do anything for Starfleet, for his ship, but he can't do this. He can't lose Bones, his best friend, the man who is more his brother than Sam ever was. Nothing is worth that.

"Don't even think about it."

Kirk's head snaps round so fast it makes his vision blur again but he ignores that. "Bones?"

McCoy looks terrible. There's no nice way of saying it. But his jaw is set, and the fire is back in his eyes as he finally meets Kirk's gaze. "Don't you dare give him what he wants, Jim. Don't give him the satisfaction."

"Think about what you're saying, Doctor," Kelvin growls, but it's too late. Kirk looks at him, and Kelvin actually takes a step back.

"He knows exactly what he's saying, and I agree with him. Do what you want with him, and with me. You will not get those codes."

The effort drains him, but he always knew it would come to this. He's a starship captain. He knew what that meant when he took command, and he still does. McCoy does too; there's pain and fear in his face but no condemnation, and Kirk realises again just how blessed he has been. Kelvin looks between the two of them and his expression hardens.

"Have it your way then." Once again he levels the revolver at McCoy.

And then the door bursts inward in a way that does nothing for Kirk's throbbing head. He makes out a figure in Science blue, but hope turns to fear as he sees Kelvin's finger tighten on the trigger.

"No!"

 _Bang!_

The gun fires. Kirk desperately scans McCoy's body, but Spock is in the way. He has one hand clasped around Kelvin's wrist, forcing the gun to the floor, and the other reaching for the man's shoulder, but Kirk has no interest in the struggle. "Bones!"

For a moment there's silence, and Kirk's heart stops. Please not now, not after all this.

"I'm all right, Jim."

Kirk has to close his eye in sheer relief. "The bullet-"

"His wound is superficial, Captain."

Kirk slumps forward at that, only to find himself supported by strong arms. "You have excellent timing, Mr. Spock," he mumbles.

He hears the click of the key being inserted into his restraints then Spock's cool voice. "I apologise for the delay, Captain. This vehicle was somewhat troublesome to access."

"I'll bet it was." The manacles fall away and he staggers, waving off Spock's offer of assistance. "Help McCoy."

Spock hesitates, his dark eyes searching Kirk's bruised face. "Captain-"

"Captain Kirk!"

Kirk ducks around Spock before the Vulcan can move to stop him and freezes. Sulu is standing by McCoy waiting for the key, but his eyes are wide and he seems frozen in place. Kirk follows his gaze and lets out a curse.

McCoy is bleeding from the neck where the bullet grazed him but that isn't what draws Kirk's attention. The doctor's eyes are fixed on the floor, unseeing, or unwilling to see, their rescuers, and his entire body is shaking so hard that only the restraints are keeping him upright. Worse is still is the sound of his breathing, harsh and rapid and becoming more so with every passing second.

Kirk swears again and darts over to him. "The key, Spock; now!"

Vulcan speed means that Spock reaches the doctor at the same moment Kirk does, but Kirk pays him no attention. "Breathe, Bones. It's over, it's all right."

It's no good. McCoy is hyperventilating worse than ever, his eyes are glazed, and Kirk is horrified to find his skin is ice cold. He doesn't even attempt to support himself as Spock releases the shackles, and only the Vulcan's quick actions keep them both from tumbling to the floor.

"Captain, what-"

"Contact the Enterprise," Kirk snaps. "He's going into shock, or something, I don't know." He holds his friend close to him, his fear deepening when McCoy gives a low moan. Kirk follows his gaze again, and his grip tightens involuntarily at the sight of Kelvin still sprawled on the ground. "And get him out of here."

Spock nods. "The brig, Captain?"

"I don't care," Kirk growls. "Just get him away from us." He turns back to Bones, ignoring the movement of his First and helmsman behind him. "It's all right, Bones; he's gone. It's over."

McCoy's shudders only seem to intensify and Kirk hugs him tighter. "I'm here, Bones," he whispers. "I'm not going to let anyone hurt you."

Then he realises what he just said and the irony almost makes him throw up. He's the reason McCoy got hurt in the first place. All of this is his fault.

"Jim."

The voice is so quiet he almost wonders if he's imagined it, but then McCoy stirs. "Jim."

"I'm here," Kirk chokes.

"K-Kelvin?"

"He's gone, Bones," said Kirk quietly. "He's gone."

He feels McCoy give a long sigh, and though the shuddering doesn't cease, his breathing calms a little. "Hobgoblin finally got here?"

Kirk has to smile at that. "Yeah, he's here."

"Good thing Vulcans have such perfect timing."

Kirk's chest hurts at the thought of what would have happened had Spock been even a minute later. McCoy's breath hitches, and Kirk forces his own distress away. "Did you just compliment Spock, Doctor?"

"He's earned it," comes the surprising reply. "If he hadn't..." His voice cracks and he ducks his head. "I'm sorry."

"Don't be an idiot," Kirk snaps. He's instantly furious with himself for letting his own stress and pain get to him, but McCoy doesn't react and that scares Jim more than anything else. "Bones? Talk to me."

McCoy shakes his head. "Nothin' you c'n do about it, Jim," he mumbles. "Can't stop your officers from bein' scared, can ya?"

Kirk bites back some choice phrases. He can hardly blame McCoy for not thinking quite straight. "The man was pointing a gun at you," he says instead. "If you weren't scared I'd be ordering you to see a psychiatrist."

McCoy's body shakes in something that might pass as laughter. "So you do have some sense of medical regulations. Was beginning to wonder."

Kirk's body relaxes automatically at the banter. McCoy will be all right, eventually. He's stronger than anyone seems to realise.

Kirk just wishes he could say the same about himself.

"Jim?"

Kirk shakes himself back to the present. "Yeah, Bones?"

"Wasn't your fault."

How does he do that? Not for the first time Kirk wonders if Spock's the only telepath on the ship. McCoy gives a soft huff. "C'mon kid, I've been patchin' you up fer three years. I know when somethin's bothering you."

Kirk looks away. "He nearly shot you."

McCoy nudges him. "Better that than he got those codes."

"I don't give a damn about the codes," Kirk snarls.

But even as he says it he knows it's a lie. McCoy gives a long sigh and shifts to look him in the eye. "You did what you had to," he says quietly. "You did exactly what you should have done."

Kirk stares unable to accept that anyone could possibly accept and forgive this so easily, but there's no lie in McCoy's eyes. Fear, yes, and bone deep exhaustion, but no blame. No hatred. And that's too much to accept. "I'm sorry," he whispers. "I'm so sorry."

McCoy looks at him for a long moment. Then, just when Kirk is beginning to wonder if he was mistaken McCoy reaches out to place his hands on Kirk's shoulders. "None of this was your fault," he repeats. "Don't you dare go blaming yourself for what that madman did."

Kirk's throat tightens. "Bones-"

"I mean it, Jim," McCoy interrupts. "He's done enough damage today. Don't...don't let him do any more."

Kirk takes a deep breath, then another, and then opens his eyes. McCoy's clouded eyes meet his, and he feels another rush of guilt. He isn't the one who needs help right now. "Okay." He shuffles forwards and wraps an arm around his friend's shoulders. "You gonna be all right?"

McCoy gives a small smile. "Don' worry about me, Jim."

Kirk just looks at him. "You're kidding, right?"

McCoy's smile disappears and he looks away. Kirk sighs, but before he can say anything there's a soft footstep and Spock enters the room. "Mr. Kelvin has been transported to the Enterprise," he says "Mr. Sulu is escorting him to the brig now."

"Thank you, Mr. Spock," says Kirk quietly. He feels McCoy's shoulders slump ever so slightly, but the doctor doesn't reply.

Spock nods, but he doesn't leave. His dark eyes study them, resting a moment longer on McCoy's still shivering body. "He was responsible for your condition."

It isn't a question but Kirk nods anyway. Spock's expression tightens in a way that Kirk has learned signals terrible consequences in store for someone, but to his surprise Spock simply moves to stand by McCoy's shoulder. "He is gone, Doctor," he says, and his voice is so gentle that Kirk stares. "He will not be permitted to harm you again."

McCoy's eyes are very wide as he finally looks at him. "Surprised you don't think my reaction is illogical."

Kirk sees a muscle work in Spock's jaw before the Vulcan replies. "The cause is sufficient." He meets Kirk's eyes, and Kirk knows he'll need to tell him the whole story soon, but not today. Now he's content to let Spock help ease McCoy's distress while he hugs their friend tighter to him and acknowledges the remainder of their silent pact.

This never happens again.

But even as he does, he has to wonder if that's really a promise he can keep.

* * *

 **Yeah, I wasn't kidding about the whump. Any feedback would be appreciated.**


	3. Duty of Care

**Apologies for the delay in getting this up, for some reason this chapter hadn't been saved with the others, and I had to track it down. Many thanks to everyone at The Beta Branch for making this legible, and thank you to my readers for all the support for this fic, I hope you enjoy this chapter.**

 **Disclaimer: I still own nothing.**

* * *

On the first day he's sure McCoy is fine.

"Jim, get the hell out of my Sickbay."

Or as fine as he can be while trying to find a cure for a deadly alien plague. "C'mon Bones, it's me."

McCoy doesn't even look at him, preoccupied as he is with the numerous test tubes and data files scattered all across his desk. "Not now."

The warning in his voice is very clear, but Kirk knows his friend and he knows exactly how far he can push this. "Bones, you haven't left this place all day. A five minute break won't hurt."

He sees the indecision on McCoy's face before the physician in him takes charge. "Fine. But just five minutes." He slumps down into the nearest chair and closes his eyes. Kirk perches very carefully on the edge of the table; he knows from experience how grouchy McCoy gets when his stuff is moved and the doctor's temper is quite bad enough already.

"You all right?"

"Yeah, I'm all right," McCoy mumbles. "Just gotta get this damn thing to work."

Kirk's eye is caught by a rack of vials set apart from the rest. "Is that it?"

McCoy's scowl deepens. "Yeah, pure samples. One of those could infect over six thousand people."

"Six thousand? And you've just got it lying around?" He can't believe his admittedly incorrigible CMO would be careless with something that dangerous, but one look at McCoy is enough to make him clamp his mouth shut. The expression on McCoy's face could stop a charging Klingon.

"It only affects Mandorites," he spits. "Damn it, Jim, do you really think I'd have something that dangerous to the crew out in the open?"

Kirk feels his cheeks heat up and he looks down. "Right. Sorry."

McCoy gives a long sigh and tilts his head back. "Me too." He rubs his eyes, stress evident in every line of his body. "Haven't been able to take a break since this stuff arrived."

Kirk frowns at him, the first warning bells starting to ring. "Bones, that was nearly thirteen hours ago. Please tell me you haven't been working on it all this time."

"Jim, this plague has infected over eight thousand people," McCoy snaps back. "What do you expect me to do, take a three course meal? Watch a movie?"

"Of course not, but you can't keep going like this. Take a break, get some food, just don't drive yourself to collapse." He takes a deep breath, forcing the concern from his voice; he knows McCoy won't appreciate it right now. "You're not a Vulcan, Bones."

"No, but I am a doctor. Unlike you."

"Bones-"

"I know what I'm doing, Jim. Just let me do my job."

Kirk looks at him. Thirteen hours of solid stress have taken their toll, but he recognises the fire burning in his best friend's eyes. "All right," he says quietly. "But at least promise me you'll eat something."

Some of the tension drains from McCoy's body. "I will."

"And get some sleep."

"Jim-"

"Do I need to make it an order?"

"I swear they had a course on this at the Academy, something about misuse of authority."

Kirk glares at him. "I prefer to call it looking after my crew."

McCoy continues to glare back. "Pity you can't feel such consideration for your own health," he mutters, but there's amusement mingled with the exasperation and Kirk allows himself to relax slightly.

"Well, why don't you start setting a good example?"

McCoy snorts. "Five minutes are up. Get outta here."

Kirk is sorely tempted to stay, but he's aware that he's already pushed his luck today. He gets to his feet and claps McCoy on the shoulder. "You'll do as I said?"

McCoy rolls his eyes. "Don' exactly have much choice, do I?" Despite his words he leans into Jim's touch for a moment before shaking himself and standing up. "Right. Back to work."

"Yeah." Kirk looks round at the mass of data surrounding them and shudders. Running a starship is easy compared to all this. "Good luck, Bones."

He's going to need it.

* * *

On the third day, Kirk begins to realise that there may be a problem.

"Bones-"

"Don't you have a ship to run?"

He suppresses the desire to remind McCoy he's talking to his commanding officer. The doctor looks so out of it Kirk's amazed he's still standing. "Bones, when was the last time you slept?"

"I don't have time to sleep!" McCoy snarls. "Not unless you want thousands of people to die slow, horrible deaths."

Kirk glances at Spock and is glad to see his own concern mirrored in the Vulcan's eyes. Both had been confused when Chapel called them down to the medbay, but Kirk was now very grateful that she had. McCoy was still working like a madman, but there could be no doubt that he was rapidly nearing exhaustion. "Bones, you promised me you were going to be careful."

He's careful to keep the accusation from his voice but McCoy still shoots him a filthy look. "Told you I'd eat. I did. Now clear off and let me work."

"I believe that would be unwise, Doctor," says Spock. "Computer records show that you have not returned to your quarters for 76.62 hours."

"And none of the lab staff have seen you stop once," Kirk adds. "Bones, you can't go over three days without sleep."

"Can too."

"Doctor-"

"Bones-"

"I'm trying to develop a cure for a goddam plague!" McCoy explodes. "I don' have time for you bargin' in here an' tellin' me how ta do my job!"

"And what good is driving yourself to the point of collapse going to do?" Kirk shouts back. Spock shoots him a look of Vulcan dismay at their volume but he ignores it; McCoy is practically dead on his feet and Kirk refuses to let him do any more damage.

"I'm fine!"

Any other time and Kirk would find the statement hysterical. He could count on one hand the number of times he's seen his friend looking less fine; McCoy is literally swaying on his feet, the shadows under his eyes are almost black, and his accent is as pronounced as Kirk has ever heard it.

Now he simply decides it's time for drastic measures. "Doctor McCoy, I am ordering you to get some sleep."

For a long moment McCoy only stares at him, his eyes darkening with shock. "What?"

Kirk steps forward, summoning every ounce of authority he possesses. "I gave you a direct order."

McCoy glares at him, the shock rapidly darkening to anger. "This is a medical matter, Captain."

He's right, but if nothing else the defiance proves just how far gone McCoy is. Kirk glances at Spock, and it's a mark of how much their relationship has improved that Spock only betrays the slightest flicker of unease at what Kirk is silently asking him to do. Kirk returns his attention to the fuming doctor, spreading his hands in a placating manner. "Why don't we all just calm down?"

McCoy scowls and turns away. "Why don' you let me do my job?"

Kirk glances at Spock but the Vulcan is already moving. McCoy doesn't even have time to turn back before Spock nerve pinches him into oblivion. The doctor crumples immediately, but Spock is there and somehow Kirk isn't at all surprised by the gentleness with which he lifts McCoy into his arms. "Thank you, Spock," he says quietly. They would have had to sedate him otherwise, and that would have been a lot harder to get away with.

"No thanks are necessary, Captain. I agree that the doctor's need for rest was greater than he was admitting."

Kirk sighs and trails him over to the nearest bio-bed. "He'd have collapsed in a couple of hours if we hadn't."

"Indeed." He deposits McCoy very carefully on the bio-bed, but there's a faint frown on his face when he turns to Kirk. "Captain, I do not believe Doctor McCoy has been eating regularly."

Kirk closes his eyes for a moment. "Now why doesn't that surprise me?"

"Because you know Doctor McCoy."

The unexpected reply startles a smile from him. "That would be it." He looks down at his unconscious friend and sighs. Trust McCoy to be so invested in a planet of strangers that he completely neglects his own health.

There's a soft footstep behind him and he tenses automatically as Nurse Chapel enters the room. He might be the captain, but she, like all the medical staff, are devoted to their CMO. He doesn't think knocking McCoy unconscious was quite what she had in mind when she called them down. To his surprise, though, undeniable relief crosses her face at the sight off McCoy asleep on the bio-bed.

"Thank you, Captain," she says softly. "We've been trying to convince him to rest, but you know how he is." She gives him an expressive look, and Kirk manages a small smile.

"Yeah, I do." He looks back to McCoy and feels his hands clench into fists. While he understands and admires his friend's dedication, there is no way he's allowing this to continue. "Who else is working on this?"

Spock raises an eyebrow. "Everyone. However, Doctor McCoy remains the only person who combines both the relevant research experience and the medical knowledge necessary to develop a cure."

"Doctor M'Benga specialises in Vulcans," Chapel reminds him gently. "Doctor McCoy has far more experience with research of this kind."

That isn't the answer he wanted. "Spock, you're the Science Officer. Isn't there anything-"

"Captain, while I do have some knowledge of medical biochemistry, it is far from my area of expertise." He sounds as frustrated with his own lack of knowledge as it's possible for a Vulcan to sound, and it's more than enough for Kirk to regret his impatience.

"I know. Sorry, Spock."

Spock inclines his head. "No apologies are unnecessary, Captain. You are not the only one who finds the current situation troubling."

Kirk has to smile. It's taken months, and more life and death situations than he can count, but Spock and McCoy are finally starting to get along. Kind of. They still fight like cats and dogs, but they are capable of showing concern for each other, even if neither of them will ever admit it. His smile fades as he looks at McCoy. He just wishes it hadn't taken these circumstances. "What are we going to do when he wakes up?"

He isn't surprised when neither of them meet his gaze. They've all been on the receiving end of a McCoy fury. Spock clasps his hands behind his back. "I would suggest we inform the doctor that we will not hesitate to resort to such measures again should he persist in overworking himself."

Chapel winces. "He's not going to like that."

"He doesn't have to like it," says Kirk quietly. "I'm not letting him do this again."

Chapel doesn't protest, but his face clearly betrays her scepticism. Kirk can't blame her. McCoy is really not going to be happy, but Kirk honestly doesn't care. If he's not going to look after himself, Kirk will just have to do it for him.

After all, it's not like there's anything else he can do to help. Not with this.

* * *

On the seventh day, Kirk begins to understand.

"Goddamn it."

Kirk is instantly on the alert. It's been hours since McCoy last spoke, other than to bark instructions down the intercom to the labs, and the tension in his voice is unmistakeable. "Bones? What is it?"

McCoy shoots him a venomous glare. "It's not working."

Kirk knows better than to take it personally. "Bones, sit down."

McCoy fumes silently, but throws himself into a chair. Kirk lets out a silent sigh of relief; McCoy might have been furious over their intervention a few days ago, but he had got the message. He suspects his friend still isn't sleeping more than two or three hours a night, but even that's better than nothing. Kirk perches on the desk next to him. "I thought you said you'd found a cure."

"We have," McCoy ground out.

"Well, that's great!"

"It's not enough!"

Kirk bites his lip. Most of the medical staff had been jubilant about the discovery, but Chapel had reported that McCoy had immediately returned to work. "Bones," he says quietly. "What's wrong?"

For a moment McCoy looks tempted to ignore him, but then his shoulders slump. "It's not a full cure," he says. "It only works if administered within a few hours of catching the disease."

"That's still good-"

"Jim, the symptoms don't start showing for nearly a day. Sure, this is great for preventing it from spreading, but there are still thousands of people who are already infected, and even more who don't even realise it." He stares up at Jim, his hazel eyes dark with helpless fury. "I can't stop yet."

Kirk pinches the bridge of his nose. He really should have known. "I get it, Bones. Really, I do. But you're exhausted. You can't keep doing this."

"I have to! And don't you dare let that hobgoblin get me again or I will have you eating nothing but salad for a month."

Kirk has no doubt that McCoy would follow through on that threat, and he has to force himself not to snap. "This is your health-"

"Which of us is the damn doctor?"

Kirk has to draw on all the self-control he's learned over the past couple of years to keep from saying what's on his mind. He can see why McCoy is so stressed, but a doctor should know better than to get himself on this state. As if sensing his thoughts, McCoy sighs and leans forward to rest his arms on his knees. "Sorry," he says softly. "Been a rough week."

Kirk allows himself to relax slightly. "I'm not counting." He shuffles over to grip McCoy's shoulder. "You've done good, Bones. As in, really good." How many other people could create a cure, even a partial one, from scratch like McCoy has? But McCoy's shoulders slump and he looks away.

"Not good enough." He gets abruptly to his feet. "I need to get back to work."

"What? Bones, you've been at this all the day."

"People are still dying, Jim. And they're going to keep dying unless we find something that actually works."

Kirk opens his mouth to point out yet again that sleep is kind of important, but pauses. For one thing McCoy is hardly likely to listen any better than he had the first dozen times, but there's something else. Jim has known McCoy for years. He knows better than anyone the lengths McCoy will go to for his patients. It isn't unusual for him to skip meals, or go without sleep, if he thinks it will help, much as he has been doing for the past week. But all Kirk's instincts are screaming that there's something else going on.

Kirk has learned to trust his instincts.

"Bones," he says quietly. "What's going on?"

"I told you-"

"I know people are dying. I want to know why you're taking this so personally."

McCoy glares at him, but Kirk doesn't back down. Something is going on here, and it's about time he found out what it is. He folds his arms and juts his chin forward and dares McCoy to tell him he's wrong.

McCoy is many things, but he's not an idiot. His shoulders slump and he looks down. "I took a closer look at Mandorite health regulations. Turns out there's a few causes they never mentioned."

Kirk feels his stomach clench. "Explain."

McCoy seems to hunch into himself. "It's an emergency protocol designed to limit the spread of an infection." A muscle in his jaw twitches. "Bastards."

"Bones," says Kirk again. "What is it?"

McCoy takes a deep even breath. "What you need to understand is that this disease doesn't kill quickly. The symptoms don't even begin to show for over a day. But it's incredibly contagious. The rate at which it spread through the population-"

"Bones," Kirk interrupts, because he has a horrible feeling he knows where this is going and if so he understands exactly what McCoy has been doing, "tell me what they can do."

"The government has up to fifteen days to secure the epidemic," says McCoy, and the pain in his voice makes Kirk feel sick. "Then extreme measures can be taken to ensure it doesn't spread further."

"How?"

McCoy looks up, and there's utter desolation in his eyes. "By killing all the infected people."

* * *

On the tenth day they find a cure. On the tenth day, Kirk knows it's only just beginning.

"How is he?"

Chapel's face is drawn with stress and fatigue, but her only concern is for her CMO. "I don't think he's had more than eight hours sleep in the past week. The stimulants and caffeine are the only reasons he's still upright." She turns to him, and her blue eyes are almost grey as they meet his. "Sir, he's going to crash, and he's going to do so hard."

It's about what he expected. It doesn't make it any easier to hear. Next to him, Spock shifts in an almost human manner. "That amount of stimulants will have serious consequences for his health."

Kirk only nods. The one time he went with stimulants over sleep for more than three days McCoy gave a truly inspired lecture on exactly how much damage he was doing to himself. He never dared to do so again. He can't even imagine doing it for a week. "He doesn't get to yell at me for at least a month."

"I really don't think that's going to be a problem," says Chapel softly.

Kirk sighs and straightens up. "Let's just get this over with."

McCoy exhibits no surprise when Kirk enters his office with Spock. Kirk is actually quite impressed that he's conscious at all all things considered, but any relief dies at the utter blankness in the doctor's eyes. Spock pauses at the door while Kirk walks round the desk to crouch in front of his friend. "Hey, Bones."

McCoy doesn't reply, doesn't respond in the slightest, and Kirk feels his concern rising. With an effort, he keeps his voice level. "Bones? It's me."

A low sigh escapes McCoy's lips. "Not like anyone can forget you."

Kirk manages a small smile. "How you doing?"

One of McCoy's shoulders rises in something that might just about pass as a shrug. "Tired. Be fine." His words are barely coherent. Kirk reaches out to grip his shoulder, and this time McCoy leans into him, too drained to resist. "Overdid it."

"Yeah, but you did it. You found the cure."

McCoy shakes his head. "Wasn' fast enough."

"Nobody could have done more than you did, Doctor," says Spock softly. He's left the doorway to stand just behind Kirk, and Kirk is grateful for the support. "Your efforts were remarkable."

Coming from Spock that's extraordinary praise, and in any other circumstances McCoy would be all over it, but this time he just shakes his head. "People died."

"They won't any more, thanks to you," Kirk insists, but he already knows it won't do any good. McCoy is far too out of it to think rationally about anything right now. Spock evidently has the same thought, for his addition is very gentle.

"Doctor, it might be advisable for you to return to your quarters."

Kirk will be amazed if McCoy can manage that, but he knows that suggesting he stays in the medbay will not go down well. As it is McCoy just sighs and closes his eyes. "Yeah."

"Agreeing with Spock," says Kirk lightly. "Now I know you're tired."

McCoy glares at him, but it's impossible to look threatening when you can't even focus on your victim. "Shuddup, Jim."

Kirk rolls his eyes and rises to his feet. "Come on. Let's get you out of here."

McCoy blinks blearily up at him. "Can' I just stay here?"

Kirk exchanges a weary glance with Spock before reaching down to pull McCoy up. "Come on, Bones. Bed is nice, remember?"

He expects McCoy to swat him, or at least glare at him. He doesn't expect McCoy's eyes to roll back in his head as he topples forward in a boneless heap.

Fortunately, Spock is a little more alert, and McCoy doesn't end up with a concussion on top of everything else. The Vulcan's only reaction is to frown at Kirk. "Captain, the doctor has lost even more weight."

Kirk sighs and pulls McCoy's arm round his shoulders. He knows Spock is more than capable of doing it himself, but he needs to do something to help. "Great."

The two of them have barely gotten McCoy onto the nearest bio-bed before Chapel joins them, her face almost white as she starts running scans. Kirk is careful to accommodate her, but he finds himself incapable of moving out of arms' reach of his friend. "Is he-"

"He'll be fine, Captain," she says, without looking at him. "But I doubt he'll wake up for a day or two, and those stimulants will leave him a bit run-down for a while."

Kirk swallows. "Damn it, Bones."

Chapel's expression softens and she reaches out to touch his arm. "He will be all right, Captain. We'll take good care of him."

Kirk can only nod. McCoy will get the best care possible; Chapel and the others practically worship the ground he walks on, though he's sure they'll have something to say about just how reckless their CMO has been. Kirk's got a few things he wants to say too.

Maybe it'll make him feel even a little bit better about not being able to do anything else.

* * *

 **Thanks for reading! Any feedback would be appreciated.**


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